Abstracts

It has been shown that different isoforms of protein kinase C (PKC) are involved in the signal transduction of the 3 groups of metabotropic glutamate receptors (mGluRs) In animal model of seizure, different subtypes of PKC isoforms have been reported to play different roles in epileptogenesis. However, no similar study has been done in the hippocampus from patients with temporal lobe epilepsy., Immunocytochemical study at both light and electron microscopic level, double immunostaining, and RT-PCR were used., In the hippocampus from patients with mesial temporal lobe epilepsy, PKC[alpha], PKC[beta], PKC[gamma], PKC[zeta], PKC[eta] and PKC[epsilon] immunopositive products decreased in the stratum pyramidale of CA1 and CA3 areas. However, no obvious change was found in CA2 area. PKC[gamma] and PKC[epsilon] immunopositive products increased in the granule cells of the dentate gyrus, however, PKC[zeta], and PKC[eta] immunopositive products decrease in these cells. Double labeling immunocytochemistry showed the co-localization of PKC[alpha], PKCg, PKC[beta]2 with metabotropic glutamate receptor 5 (mGluR5), G-protein subtype G[sub]q/11 [/sub][alpha] and phospholipids C beta1 subtype (PLC[beta]1) in pyramidal neurons in CA1-3 areas.
Under electron microscopic level, PKC[delta], PKC[eta], PKC[zeta], or PKC[epsilon] was located in the post-synaptic elements. However, PKC[gamma] was found in both pre- and post-synaptic elements.
Gene expression of different isoforms of PKC such as PKC[alpha], PKC[beta], PKC[gamma], PKC[zeta], PKC[eta] and PKC[epsilon] has been studied by RT-PCR in the hippocampus of the [ldquo]normal[rdquo] human samples. We showed relative lower expression of PKC[beta] when compared to other PKC isoforms., PKC[gamma] and PKC[epsilon] may be related to the hyperactivity of granular cells and involved in epileptogenesis. PKC[alpha], PKCg, PKC[beta]2 may be involved in mGluR5, G[sub]q/11 [/sub][alpha] and PLC[beta]1 related signal transduction in pyramidal neurons., (Supported by a research grant from National Medical Research Council (No: NMRC/0731/2003).)